In the xy-coordinate plane,lines L and Q are perpendicular.If line L contains the points (0,0) and (

题目

In the xy-coordinate plane,lines L and Q are perpendicular.If line L contains the points (0,0) and (2,1),and line Q contains the points (2,1) and (0,T),what is the value of

答案

L和Q 垂直.
L 过（0 0） （2,1）所以L 这条线是y=0.5x,所以Q的斜率是-2,对吧.因为垂直 斜率是负倒数.
Q过（2,1）（0,t）所以-2(2)+t=1 推出t=5
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